Insights on Osmotic Tolerance Mechanisms in Escherichia coli Gained from an rpoC Mutation

An 84 bp in-frame duplication (K370_A396dup) within the rpoC subunit of RNA polymerase was found in two independent mutants selected during an adaptive laboratory evolution experiment under osmotic stress in , suggesting that this mutation confers improved osmotic tolerance. To determine the role th...

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Bibliographic Details
Published in:Bioengineering (Basel) 2017-06, Vol.4 (3), p.61
Main Authors: Guo, Yuqi, Winkler, James, Kao, Katy C
Format: Article
Language:English
Subjects:
Acetic acid
amino acid
Amino acids
Bacteria
Binding sites
Bioengineering
Cell membranes
Clonal deletion
complex phenotype
Damage assessment
Damage tolerance
DNA-directed RNA polymerase
E coli
Escherichia coli
Fermentation
Gene deletion
Genes
Genomics
membrane integrity
Metabolism
Metabolites
Methionine
Microorganisms
Mutation
Osmosis
Osmotic stress
osmotic tolerance
Potassium
Proline
Raw materials
Ribonucleic acid
RNA
RNA polymerase
rpoC
Sodium chloride
Stresses
Sulfur
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Summary:An 84 bp in-frame duplication (K370_A396dup) within the rpoC subunit of RNA polymerase was found in two independent mutants selected during an adaptive laboratory evolution experiment under osmotic stress in , suggesting that this mutation confers improved osmotic tolerance. To determine the role this mutation in plays in osmotic tolerance, we reconstructed the mutation in BW25113, and found it to confer improved tolerance to hyperosmotic stress. Metabolite analysis, exogenous supplementation assays, and cell membrane damage analysis suggest that the mechanism of improved osmotic tolerance by this mutation may be related to the higher production of acetic acid and amino acids such as proline, and increased membrane integrity in the presence of NaCl stress in exponential phase cells. Transcriptional analysis led to the findings that the overexpression of methionine related genes and improves osmotic tolerance in BW25113. Furthermore, deletion of a stress related gene was found to confer enhanced osmotic tolerance in BW25113 and MG1655. These findings expand our current understanding of osmotic tolerance in , and have the potential to expand the utilization of high saline feedstocks and water sources in microbial fermentation.
ISSN:2306-5354
2306-5354
DOI:10.3390/bioengineering4030061